CATALOGUE OF PLANTS. 271 



Var. serpentina, Ach. 



Thallus ash-colored, tartareous, thicker than that of the 

 preceding species, pulverulent, fissured, clearly determinate. 

 Apothecia crowded, sunken, much elongated, simple or branched. 

 Spores similar to preceding. On trees. Southwest Harbor (M. 

 L. Fernald). 



* G. dendritica, Ach. 



Thallus cream-colored to a yellowish ash color, thin, tartareous, 

 mealy. Apothecia brownish black, immersed, divided in branch- 

 like clusters or pedate divisions. Spores long, linear, 6-8-sep- 

 tate, $$jfo mic. Seal Harbor (Eckfeldt). 



ARTHONIEI. 



ARTHONIA, Ach.* 



* A. punctiformis, Ach. 



Thallus whitish, quite distinct or fading to a mere film. 

 Apothecia very small, roundish or irregularly elongated, be- 

 coming variable in shape, often stellate. Spores long, ovoid, 



mostly 4-locular, ^'003 m * c - O n tree barks. Southwest Har- 

 bor (Eckfeldt). 



* A. astroidea, Ach. 



Thallus pale ash-colored, opaque, finally almost wanting, but 

 differing in color from the substrata, marginate with a waving 

 terminal darkening line. Apothecia diverse, mostly stellate, 

 slightly elevated, convex, pallid internally. Spores ovoid to 

 elongated, 4-locular, ^^-^ mic. On tree barks. Southwest 

 Harbor (Eckfeldt). 



* Var. Swartzoidea, Nyl. 



Thallus pale ash-colored, opaque but differing in color from the 

 substrata, often becoming darker and more clearly distinct. Apo- 

 thecia well pronounced, mostly round or irregular, '^''^ mic - 

 On tree barks. Southwest Harbor (Eckfeldt). 



*For description of genus, see Tuck., Syn. N. A. Lichens, part L, 12. 



